Position correction method, program, and position correction device

Abstract

To provide a position correction method capable of easily correcting a position of a hand with respect to a mold.SOLUTION: This position correction method comprises: (a) a step of photographing a mark 18 by a camera 10 so as to set the mark 18 of a mold 6 at a prescribed position in a photographed image, when the mold 6 is at a proper position; (b) a step of calculating mark reference coordinates on the basis of robot coordinates indicating the position of an articulated robot 8 when the mark 18 is photographed in (a); (c) a step of photographing the mark 18 by the camera 10 in a state where the articulated robot 8 is at a teaching position when the mold 6 is displaced from the proper position to a displacement position; (d) a step of calculating mark displacement coordinates on the basis of the displacement amount of mark 18 from a prescribed position in a photographed image photographed in (c); and (e) a sep of calculating a correction value of the position of a hand 28 with the mold 6 on the basis of the mark reference coordinates and the mark displacement coordinates.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a position correction method, a program, and a position correction device for correcting the position of a hand unit of an articulated robot with respect to a die. [Background technology]

[0002] In an automated device for insert molding, a part insertion device equipped with a multi-joint robot is often used (for example, see Patent Document 1). The multi-joint robot has a multi-joint arm and a hand unit arranged at the tip of the multi-joint arm. In this part insertion device, first, the insert part is grasped by the hand unit, and then the hand unit is moved in a horizontal direction (a surface direction parallel to the parting surface of the mold) relative to a mold that is detachably attached at an appropriate position on a die plate (hereinafter simply referred to as "die plate") of a molding machine, thereby positioning the insert part directly above an insert hole formed in the upper surface, which is the parting surface of the mold. Finally, the hand unit is moved downward toward the upper surface of the mold, thereby inserting the insert part into the insert hole of the mold. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-94719 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned component insertion device, the die may be removed from the die plate to perform maintenance (e.g., cleaning, etc.) of the die. When the die is reattached to the die plate after the maintenance is completed, the attachment position of the die with respect to the die plate may be displaced from the above-mentioned appropriate position.

[0005] Therefore, with conventional part insertion devices, each time the die is attached or detached from the die plate, the operating program or teaching position of the articulated robot must be manually modified to correct the insert position of the insert part, which is very time-consuming.

[0006] The present invention seeks to solve the above-mentioned problems, and its object is to provide a position correction method, program, and position correction device that can easily correct the position of a hand part of a multi-joint robot relative to a mold. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, a position correction method according to a first aspect of the present invention is a position correction method for correcting the position of a hand unit of a multi-joint robot with respect to a mold, the position correction method including the steps of: (a) photographing a mark arranged on a surface of the mold with a camera arranged on the hand unit when the mold is located at an appropriate position, so that the mark is located at a predetermined position in the photographed image; (b) calculating mark reference coordinates indicating a reference position of the mark based on robot coordinates indicating the position of the multi-joint robot when the mark was photographed in (a); (c) photographing the mark with the camera when the mold is displaced from the appropriate position to a displaced position, while the multi-joint robot is located at a teaching point, which is the position of the multi-joint robot when the mark was photographed in (a); (d) calculating mark displacement coordinates indicating the displaced position of the mark based on the amount of displacement of the mark from the predetermined position in the photographed image taken in (c); and (e) calculating a correction value for the position of the hand unit with respect to the mold based on the mark reference coordinates and the mark displacement coordinates.

[0008] According to this aspect, when the mold is displaced from the appropriate position to the displaced position, there is no need to manually modify the operating program or teaching position of the articulated robot, and the position of the hand part of the articulated robot relative to the mold can be easily corrected.

[0009] For example, in a position correction method according to a second aspect of the present invention, in the first aspect, the multi-joint robot has an arm section and a hand section that is arranged at the tip of the arm section and is rotatable around a rotation axis relative to the arm section, and in (a), (i) when the hand section is in a first rotation position relative to the arm section, the mark is photographed by the camera so that the mark is located at the predetermined position in a first captured image, and then (ii) when the hand section is in a second rotation position rotated by a predetermined rotation angle from the first rotation position relative to the arm section, the mark is photographed by the camera so that the mark is located at the predetermined position in a second captured image, and in (b), the mark reference coordinates may be calculated based on first robot coordinates indicating the position of the multi-joint robot when the first captured image was taken, second robot coordinates indicating the position of the multi-joint robot when the second captured image was taken, and the predetermined rotation angle.

[0010] According to this aspect, the mark reference coordinates can be calculated easily and accurately.

[0011] For example, in a position correction method according to a third aspect of the present invention, in the first or second aspect, the mold is formed in a rectangular shape, the marks include a first mark, a second mark, a third mark, and a fourth mark arranged corresponding to four corners on the surface of the mold, the first mark and the fourth mark are arranged diagonally, and the second mark and the third mark are arranged diagonally, and in (e), (i) a displacement amount of the mark in two mutually perpendicular directions from the predetermined position in the captured image captured in (c), and (ii) a coordinate system connecting the mark reference coordinate indicating the reference position of the first mark and the mark reference coordinate indicating the reference position of the fourth mark when the mold is located at the appropriate position are measured. a first intersection coordinate indicating a position of an intersection between a first straight line and a second straight line connecting the mark reference coordinates indicating the reference position of the second mark and the mark reference coordinates indicating the reference position of the third mark; a third straight line connecting the mark displacement coordinates indicating the displacement position of the first mark and the mark displacement coordinates indicating the displacement position of the fourth mark in a state where the die is displaced from the appropriate position to the displacement position, and a fourth straight line connecting the mark displacement coordinates indicating the displacement position of the second mark and the mark displacement coordinates indicating the displacement position of the third mark; and an angle formed by the first straight line and the third straight line in a state where the first intersection coordinates and the second intersection coordinates coincide with each other is calculated as the correction value.

[0012] According to this aspect, the correction value can be calculated easily and accurately.

[0013] For example, in the position correction method according to the fourth aspect of the present invention, in any one of the first to third aspects, the marks may be configured to be arranged in multiple numbers on the surface of the mold.

[0014] According to this aspect, the correction value can be corrected with higher accuracy.

[0015] For example, in the position correction method according to the fifth aspect of the present invention, in any one of the first to fourth aspects, the mark may be formed in a substantially circular shape.

[0016] According to this aspect, since there is no need to consider the orientation of the camera when photographing the mark, the position of the hand portion of the articulated robot relative to the mold can be more easily corrected.

[0017] For example, in a position correction method according to a sixth aspect of the present invention, in any one of the first to fifth aspects, the mold may be a mold for insert molding having an insert hole formed in the surface, and the hand portion of the articulated robot may be configured to be capable of grasping an insert part to be inserted into the insert hole.

[0018] According to this aspect, the insert position of the insert part held by the hand portion can be easily corrected.

[0019] For example, a program according to a seventh aspect of the present invention causes a computer to execute the position correction method according to any one of the first to sixth aspects.

[0020] Further, a position correction device according to an eighth aspect of the present invention is a position correction device for correcting a position of a hand unit of a multi-joint robot with respect to a mold, the position correction device comprising a processor and a memory, and the processor uses the memory to execute control to (a) when the mold is located at an appropriate position, photograph a mark arranged on the surface of the mold with a camera arranged on the hand unit so that the mark is located at a predetermined position in the photographed image, (b) calculate mark reference coordinates indicating a reference position of the mark based on robot coordinates indicating the position of the multi-joint robot when the mark was photographed in (a), (c) when the mold is displaced from the appropriate position to a displaced position, photograph the mark with the camera while the multi-joint robot is located at a teaching point which is the position of the multi-joint robot when the mark was photographed in (a), (d) calculate mark displacement coordinates indicating the displaced position of the mark based on the amount of displacement of the mark from the predetermined position in the photographed image taken in (c), and (e) calculate a correction value for the position of the hand unit with respect to the mold based on the mark reference coordinates and the mark displacement coordinates.

[0021] According to this aspect, when the mold is displaced from the appropriate position to the displaced position, there is no need to manually modify the operating program or teaching position of the articulated robot, and the position of the hand part of the articulated robot relative to the mold can be easily corrected. Effect of the Invention

[0022] According to the position correction method and the like relating to one aspect of the present invention, the position of a hand part of an articulated robot with respect to a mold can be easily corrected. [Brief description of the drawings]

[0023] [Figure 1A] 1 is a perspective view showing an external appearance of a component insertion device according to an embodiment; [Figure 1B] 1 is a schematic diagram showing an external appearance of a component insertion device according to an embodiment; [Diagram 2]2 is a schematic perspective view showing a hand unit and a die of the component insertion device according to the embodiment. FIG. [Diagram 3] 1 is a block diagram showing a configuration of a position correction device according to an embodiment; [Figure 4] 5 is a flowchart showing a flow of operations of the position correction device according to the embodiment. [Diagram 5] FIG. 5 is a diagram for explaining the process of step S102 in the flowchart of FIG. [Figure 6] FIG. 5 is a diagram for explaining the process of step S103 in the flowchart of FIG. [Figure 7] FIG. 5 is a diagram for explaining the process of step S103 in the flowchart of FIG. [Figure 8] FIG. 5 is a diagram for explaining the process of step S103 in the flowchart of FIG. [Figure 9] FIG. 5 is a diagram for explaining the process of step S104 in the flowchart of FIG. [Figure 10] FIG. 5 is a diagram for explaining the process of step S104 in the flowchart of FIG. [Figure 11] FIG. 5 is a diagram for explaining the process of step S104 in the flowchart of FIG. [Figure 12] FIG. 5 is a diagram for explaining the process of step S105 in the flowchart of FIG. [Figure 13] FIG. 5 is a diagram for explaining the process of step S106 in the flowchart of FIG. [Figure 14] FIG. 5 is a diagram for explaining the process of step S106 in the flowchart of FIG. [Figure 15] FIG. 5 is a diagram for explaining the process of step S106 in the flowchart of FIG. [Figure 16] FIG. 5 is a diagram for explaining the process of step S106 in the flowchart of FIG. [Figure 17] FIG. 5 is a diagram for explaining the process of step S106 in the flowchart of FIG. [Figure 18]FIG. 5 is a diagram for explaining the process of step S106 in the flowchart of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the present invention. Furthermore, among the components in the following embodiments, components that are not described in the independent claims will be described as optional components.

[0025] (Embodiment) [1. Configuration of component insertion device] First, a configuration of a component insertion device 2 according to an embodiment will be described with reference to Figs. 1A to 3. Fig. 1A is a perspective view showing an external appearance of the component insertion device 2 according to an embodiment. Fig. 1B is a schematic view showing an external appearance of the component insertion device 2 according to an embodiment. Fig. 2 is a schematic perspective view showing a hand unit 28 and a die 6 of the component insertion device 2 according to an embodiment. Fig. 3 is a block diagram showing a configuration of a position correction device 12 according to an embodiment.

[0026] 1A to 2, the left-right direction of the mold 6 will be described as the X-axis direction, the front-rear direction of the mold 6 as the Y-axis direction, and the up-down direction of the mold 6 as the Z-axis direction. The positive side in the Z-axis direction will be described as "up" and the negative side in the Z-axis direction will be described as "down".

[0027] The part insertion device 2 according to the embodiment is a device used in an automated device for insert molding, which is a type of injection molding. As shown in Fig. 1A, the part insertion device 2 includes a die plate 4, a die 6, an articulated robot 8, a camera 10, and a position correction device 12. In reality, the part insertion device 2 and the die 6 have the configuration shown in Fig. 1A, but in the following, for ease of understanding, the respective configurations of the part insertion device 2 and the die 6 are simplified and described as shown in Fig. 1B and Fig. 2.

[0028] The die plate 4 is a base for detachably mounting the die 6. The upper surface of the die plate 4 is formed flat so that the die 6 can be placed thereon.

[0029] The mold 6 is a mold for insert molding, and is formed, for example, in a rectangular flat plate shape in an XY plane view. The mold 6 is detachably attached to the die plate 4 by, for example, a plurality of bolts (not shown). As shown in FIG. 2, a pair of insert holes 14, 16 are formed in the surface 6a, which is the parting surface of the mold 6. The pair of insert holes 14, 16 are arranged at an interval in the left-right direction (X-axis direction). Each of the pair of insert holes 14, 16 is formed, for example, in a circular cross section, and extends along the thickness direction (Z-axis direction) of the mold 6. Each of the pair of insert holes 14, 16 has a diameter of, for example, about 5 mm. In this embodiment, the pair of insert holes 14, 16 is formed in the mold 6, but is not limited to this, and one or three or more insert holes may be formed. In this embodiment, the mold 6 is described as a type that opens and closes vertically, but is not limited to this, and the mold 6 may be a type that opens and closes horizontally.

[0030] Further, a plurality of marks 18, 20, 22, 24 (18-24) are arranged near each of the four corners on the surface 6a of the mold 6. Here, the mark 18 is an example of a first mark, the mark 20 is an example of a second mark, the mark 22 is an example of a third mark, and the mark 24 is an example of a fourth mark. The marks 18 and 24 are arranged diagonally, and the marks 20 and 22 are arranged diagonally.

[0031] Each of the marks 18 to 24 has, for example, a substantially circular shape. Each of the marks 18 to 24 is formed by engraving the surface 6a of the mold 6 by cutting. Alternatively, each of the marks 18 to 24 may be formed by, for example, printing or painting, or by attaching an adhesive sticker to the surface 6a of the mold 6.

[0032] The articulated robot 8 has an articulated arm section 26 (an example of an arm section) and a hand section 28.

[0033] The articulated arm unit 26 changes the position of the hand unit 28 in the X-axis direction, the Y-axis direction, and the Z-axis direction (i.e., three-dimensionally) within a predetermined working area. A disk-shaped tool flange 30 is rotatably supported at the tip of the articulated arm unit 26a.

[0034] The hand unit 28 is formed, for example, in a substantially T-shaped flat plate shape when viewed in the XY plane, and has a support unit 28a and a grip unit 28b. The support unit 28a extends laterally from the center of the grip unit 28b in the longitudinal direction. Note that, in the present embodiment, the hand unit 28 is formed in a substantially T-shaped flat plate shape when viewed in the XY plane, but is not limited thereto, and may be formed in any shape, such as an I-shaped flat plate shape.

[0035] The support portion 28a of the hand portion 28 is disposed at the tip of the articulated arm portion 26. More specifically, the support portion 28a of the hand portion 28 is supported at the tip of the articulated arm portion 26 via a tool flange 30 so as to be rotatable about a rotation axis 32. The rotation axis 32 passes through the radial center of the tool flange 30 and is a straight line parallel to the up-down direction. A pair of insert parts 34, 36 can be held on the lower surface of the gripping portion 28b of the hand portion 28. Each of the pair of insert parts 34, 36 is, for example, a cylindrical metal part or the like used in insert molding. The diameters of the pair of insert parts 34, 36 are smaller than the diameters of the pair of insert holes 14, 16 of the mold 6.

[0036] In insert molding, first, as shown in Fig. 2, the pair of insert parts 34, 36 are positioned directly above the pair of insert holes 14, 16 of the mold 6, which are the respective insert positions, and the articulated arm unit 26 moves the hand unit 28 downward toward the surface 6a of the mold 6. As a result, the pair of insert parts 34, 36 are inserted into the pair of insert holes 14, 16, respectively. Next, molding resin is injected into the surface 6a of the mold 6, thereby producing an insert molded product in which the pair of insert parts 34, 36 and the resin are integrally molded.

[0037] In this embodiment, each of the pair of insert parts 34, 36 is formed in a cylindrical shape, but is not limited thereto, and may be formed in a rectangular prism shape, or in a complex shape such as a connector pin. In this case, the cross-sectional shapes of the pair of insert holes 14, 16 of the mold 6 are approximately the same as the cross-sectional shapes of the pair of insert parts 34, 36. In reality, a gap of, for example, about 0.01 to 0.03 mm is formed between the insert hole 14 and the insert part 34, and between the insert hole 16 and the insert part 36.

[0038] The camera 10 is disposed on the side surface of the gripping portion 28b of the hand portion 28. When the hand portion 28 is positioned above the surface 6a of the mold 6, the camera 10 captures an image of the surface 6a of the mold 6 from above.

[0039] The position correction device 12 is a device for correcting the position of the hand unit 28 of the articulated robot 8 relative to the mold 6 (i.e., each insert position of a pair of insert parts 34, 36). As shown in FIG. 3, the position correction device 12 has a processor 38 and a memory 40. The processor 38 controls the photographing operation of the camera 10. The processor 38 also acquires an image captured by the camera 10, and calculates a correction value for correcting the position of the hand unit 28 relative to the mold 6 by executing a program stored in the memory 40 based on the acquired captured image. The processor 38 then controls the driving of the articulated robot 8 based on the calculated correction value.

[0040] [2. Operation of position correction device] [2-1. Overall operation of the position correction device] Next, the overall operation of the position correction device 12 according to the embodiment will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the flow of the operation of the position correction device 12 according to the embodiment.

[0041] As shown in FIG. 4, first, the camera 10 is attached to the hand unit 28 of the articulated robot 8 (S101).

[0042] Next, the processor 38 of the position correction device 12 identifies a location that matches the matching image from the image of the die 6 captured by the camera 10 (S102).

[0043] Next, the processor 38 causes the coordinate axes of the articulated robot 8 (hereinafter referred to as "robot coordinate axes") to coincide with the coordinate axes of the camera 10 (hereinafter referred to as "camera coordinate axes") (S103).

[0044] Next, the processor 38 calculates a plurality of mark reference coordinates indicating the respective reference positions of the plurality of marks 18 to 24 (S104).

[0045] Next, the processor 38 calculates a plurality of mark displacement coordinates indicating the displacement positions of the plurality of marks 18 to 24, respectively (S105).

[0046] Next, the processor 38 calculates a correction value for correcting the position of the hand unit 28 with respect to the mold 6, based on the plurality of mark reference coordinates and the plurality of mark displacement coordinates (S106).

[0047] Each of the processes in steps S101 to S106 described above will now be described in detail.

[0048] [2-2. Processing of step S101] The process of step S101 described above will be described with reference to Fig. 1B. As shown in Fig. 1B, an operator or the like attaches the camera 10 to the side of the hand unit 28 of the articulated robot 8 so that the lens surface of the camera 10 is parallel to the surface 6a of the mold 6 and the optical axis of the camera 10 is perpendicular to the surface 6a of the mold 6.

[0049] In steps S101 to S104, it is assumed that the die 6 is attached to the die plate 4 at a proper position (that is, at a position where the pair of insert parts 34, 36 can be inserted into the pair of insert holes 14, 16, respectively).

[0050] [2-3. Processing of step S102] The process of step S102 described above will be described with reference to Fig. 5. Fig. 5 is a diagram for explaining the process of step S102 in the flowchart of Fig. 4.

[0051] The processor 38 registers in advance a matching image 42 shown in Fig. 5(a). The matching image 42 is an image showing a sample of a mark.

[0052] Next, the processor 38 acquires a captured image 44 shown in Fig. 5(b) which is an image of a part of the surface 6a of the mold 6 from the camera 10. Next, the processor 38 identifies a portion (e.g., the mark 18) from the captured image 44 that matches the matching image 42 shown in Fig. 5(a), and acquires matching coordinates which are the coordinates of the center of the identified portion.

[0053] [2-4. Processing of step S103] The process of step S103 described above will be described with reference to Figures 6 to 8. Figures 6 to 8 are diagrams for explaining the process of step S103 in the flowchart of Figure 4.

[0054] As shown in FIG. 6, the robot coordinate axes have world coordinate axes (X1-Y1 coordinate axes) and tool coordinate axes (X2-Y2 coordinate axes). The world coordinate axes are coordinate axes based on the articulated arm unit 26. The tool coordinate axes are coordinate axes based on the rotation angle of the tool flange 30. When the rotation angle of the tool flange 30 is 0°, the tool coordinate axes coincide with the world coordinate axes. On the other hand, the camera coordinate axes (X3-Y3 coordinate axes) vary depending on, for example, the rotation angle of the tool flange 30.

[0055] Since the robot coordinate axes and the camera coordinate axes are different from each other in this way, it is necessary to make them coincide with each other as follows.

[0056] First, the processor 38 drives the articulated arm unit 26 so that the camera 10 moves to above the mark 18 on the mold 6 , and causes the camera 10 to photograph the mark 18 .

[0057] Next, as shown in (a) of FIG. 7, the processor 38 drives the articulated arm unit 26 so that the mark 18 is positioned at one end in the captured image 46 captured by the camera 10, and acquires the matching coordinates of the mark 18 in this state.

[0058] Next, as shown in (b) of Figure 7, the processor 38 drives the articulated arm unit 26 so that the mark 18 is positioned at the other end (the end opposite to the above-mentioned one end) in the captured image 48 captured by the camera 10, and obtains the matching coordinates of the mark 18 in this state.

[0059] Next, as shown in FIG. 8(a), the processor 38 acquires the matching coordinates of the two marks 18 from the two captured images 46, 48, respectively.

[0060] Next, as shown in FIG. 8(b), the processor 38 calculates the angle φ between a line 50 connecting the two matching coordinates and a reference line 52 extending horizontally while the two captured images 46, 48 are superimposed.

[0061] 8(c), the processor 38 rotates the camera coordinate axes by the calculated angle φ so that the straight line 50 coincides with the reference line 52. This allows the camera coordinate axes to coincide with the tool coordinate axes of the robot coordinate axes. In each of the subsequent steps, the processor 38 performs coordinate conversion in an internal process to obtain each coordinate where the camera coordinate axes coincide with the tool coordinate axes of the robot coordinate axes.

[0062] [2-5. Processing of step S104] The process of step S104 described above will be described with reference to Figures 9 to 11. Figures 9 to 11 are diagrams for explaining the process of step S104 in the flowchart of Figure 4.

[0063] 9(a), the processor 38 drives the articulated arm unit 26 so that the camera 10 moves to above the mark 18 on the mold 6, causing the camera 10 to photograph the mark 18. At this time, the hand unit 28 is in a first rotation position relative to the articulated arm unit 26. The processor 38 calculates the distance x1 in the x-axis direction and the distance y1 in the y-axis direction from the coordinates of the mark 18 to the coordinates of the center of the photographed image 54 on the camera coordinate axes (=robot coordinate axes).

[0064] Next, as shown in FIG. 9B, the processor 38 drives the articulated arm unit 26 to move the camera 10 by a distance corresponding to the calculated distance x1 in the x-axis direction and distance y1 in the y-axis direction. As a result, the mark 18 moves to the center (an example of a predetermined position) of the captured image 54 (an example of a first captured image), and the coordinates of the mark 18 become coincident with the coordinates of the center of the captured image 54. The processor 38 also calculates first robot coordinates (xa, ya) indicating the position of the articulated robot 8 at this time (specifically, the position of the radial center of the tool flange 30). The processor 38 stores the calculated first robot coordinates (xa, ya) as a teaching point.

[0065] 10, the processor 38 rotates the hand unit 28 by a predetermined rotation angle A with respect to the articulated arm unit 26, from the first rotation angle to the second rotation angle. Next, the processor 38 drives the articulated arm unit 26 to move the camera 10, in the same manner as described above, so that the mark 18 moves to the center of the captured image 56 (an example of a second captured image). The processor 38 also calculates second robot coordinates (xb, yb) indicating the position of the articulated robot 8 at this time (specifically, the position of the radial center of the tool flange 30).

[0066] Next, as shown in FIG. 11, the processor 38 calculates the mark reference coordinates indicating the reference position of the mark 18 (i.e., the position of the mark 18 in the mold 6 located in the appropriate position) by calculating a rotation matrix using the acquired first robot coordinates (xa, ya) and second robot coordinates (xb, yb) and the rotation angle A of the hand unit 28.

[0067] Similarly, the processor 38 calculates the mark reference coordinates indicating the reference position of the other three marks 20, 22, and 24, that is, the mark reference coordinates indicating the reference position of the mark 20, the mark reference coordinates indicating the reference position of the mark 22, and the mark reference coordinates indicating the reference position of the mark 24.

[0068] [2-6. Processing of step S105] The process of step S105 described above will be described with reference to Fig. 12. Fig. 12 is a diagram for explaining the process of step S105 in the flowchart of Fig. 4.

[0069] The processor 38 causes the camera 10 to photograph the mark 18 while the articulated robot 8 is positioned at a teaching point corresponding to the mark 18. At this time, if the die 6 is positioned at an appropriate position on the die plate 4, the mark 18 will be positioned at the center of the image photographed by the camera 10.

[0070] On the other hand, when the die 6 is attached to or detached from the die plate 4 for maintenance of the die 6, the die 6 may be displaced from the appropriate position on the die plate 4 (position indicated by the dashed line in FIG. 12) to a displaced position (position indicated by the solid line in FIG. 12) as shown in FIG. 12. In this case, the mark 18 is located at a position displaced from the center of the captured image 58 captured by the camera 10. The processor 38 calculates the distance x in the X3 axis direction and the distance y in the Y3 axis direction (i.e., the amount of displacement in two mutually perpendicular directions) from the coordinates of the mark 18 to the coordinates of the center of the captured image 58 on the camera coordinate axes. Then, the processor 38 acquires the calculated x and y as correction values.

[0071] In the same manner, the processor 38 calculates the correction values ​​x and y for the other three marks 20, 22, and 24, respectively.

[0072] Next, the processor 38 calculates the mark displacement coordinates of the mark 18 based on the mark reference coordinates of the mark 18 and the correction values ​​x, y corresponding to the mark 18. The processor 38 also calculates the mark displacement coordinates of the mark 20 based on the mark reference coordinates of the mark 20 and the correction values ​​x, y corresponding to the mark 20. The processor 38 also calculates the mark displacement coordinates of the mark 22 based on the mark reference coordinates of the mark 22 and the correction values ​​x, y corresponding to the mark 22. The processor 38 also calculates the mark displacement coordinates of the mark 24 based on the mark reference coordinates of the mark 24 and the correction values ​​x, y corresponding to the mark 24.

[0073] [2-7. Processing of step S106] The process of step S106 described above will be described with reference to Figures 13 to 18. Figures 13 to 18 are diagrams for explaining the process of step S106 in the flowchart of Figure 4.

[0074] 13(a), the processor 38 calculates first intersection coordinates indicating the position of intersection G of the mold 6 located at the appropriate position from the mark reference coordinates of each of the multiple marks 18 to 24. This intersection G is the intersection of a first line connecting the mark reference coordinates indicating the reference position of mark 18 and the mark reference coordinates indicating the reference position of mark 24, and a second line connecting the mark reference coordinates indicating the reference position of mark 20 and the mark reference coordinates indicating the reference position of mark 22, when the mold 6 is located at the appropriate position.

[0075] 13(b), the processor 38 calculates second intersection coordinates indicating the position of the intersection G of the mold 6 located at the displacement position from the mark displacement coordinates of each of the marks 18 to 24. This intersection G is the intersection of a third line connecting the mark displacement coordinates indicating the displacement position of the mark 18 and the mark displacement coordinates indicating the displacement position of the mark 24 and a fourth line connecting the mark displacement coordinates indicating the displacement position of the mark 20 and the mark displacement coordinates indicating the displacement position of the mark 22 in a state in which the mold 6 is displaced from the appropriate position to the displacement position.

[0076] Next, the processor 38 calculates, as a correction value, an angle θ between a first straight line shown by a dashed line in Fig. 13(a) and a third straight line shown by a dashed line in Fig. 13(b) when the intersection point G shown in Fig. 13(a) and the intersection point G shown in Fig. 13(b) coincide with each other. The processor 38 may also calculate, as a correction value, an angle θ between a second straight line shown by a dashed line in Fig. 13(a) and a fourth straight line shown by a dashed line in Fig. 13(b) when the intersection point G shown in Fig. 13(a) and the intersection point G shown in Fig. 13(b) coincide with each other.

[0077] In the present embodiment, the processor 38 calculates the first intersection coordinates indicating the position of the intersection G between the first line and the second line, and the second intersection coordinates indicating the position of the intersection G between the third line and the fourth line, but is not limited to this. For example, when the number of marks arranged on the surface of the mold 6 is two, the processor 38 may calculate the midpoint coordinates indicating the position of the midpoint between the two marks. Also, for example, when the number of marks arranged on the surface of the mold 6 is three, the processor 38 may calculate the barycentric coordinates indicating the position of the center of gravity of a triangle having the three marks as its vertices.

[0078] 14, when the hand unit 28 is rotated by the correction value θ relative to the articulated arm unit 26 (see FIG. 1B), the position of the camera 10 moves significantly before and after the rotation of the hand unit 28. This is because, in the XY plane view, the camera 10 is separated from the rotation axis 32, which is the rotation center of the hand unit 28. Taking this into consideration, the processor 38 calculates a correction value θxy, which will be described later.

[0079] 15, when the die 6 is displaced from the appropriate position on the die plate 4 to a displaced position, when the hand unit 28 moves to a position before correction (i.e., a pre-programmed position for executing the insert of the pair of insert parts 34, 36) (hereinafter referred to as the "insert execution position"), the insert positions of the pair of insert parts 34, 36 are displaced with respect to the pair of insert holes 14, 16, respectively. Therefore, it is necessary to correct the insert execution position of the hand unit 28 with respect to the die 6 using the above-mentioned correction value θ and correction values ​​x, y.

[0080] 16, the processor 38 drives the articulated arm unit 26 to rotate the hand unit 28 by the correction value θ relative to the mold 6 around the radial center (rotation axis 32) of the tool flange 30. At this time, since each of the pair of insert parts 34, 36 is spaced apart from the radial center of the tool flange 30, the amount of movement of each of the pair of insert parts 34, 36 accompanying the rotation of the hand unit 28 becomes large. Therefore, at this stage, the insert positions of the pair of insert parts 34, 36 do not match the pair of insert holes 14, 16, respectively.

[0081] 17, the processor 38 drives the articulated arm unit 26 to move the hand unit 28 horizontally (i.e., within the XY plane) by the correction values ​​x, y relative to the mold 6. Here, the horizontal direction is a planar direction parallel to the surface 6a of the mold 6. Even at this stage, the insert positions of the pair of insert parts 34, 36 do not coincide with the pair of insert holes 14, 16, respectively.

[0082] Next, when a straight line connecting a specific mark (e.g., mark 24) among the multiple marks 18-24 and the moved insert position as shown in Fig. 17 is defined as R, processor 38 performs coordinate axis transformation using straight line R and correction value θ. Next, processor 38 calculates the difference between the moved insert position and the position where the coordinate axis transformation has been performed, and obtains the calculated difference as correction value θxy.

[0083] 18, the processor 38 drives the articulated arm unit 26 to rotate the hand unit 28 by the correction value θxy around a specific mark (e.g., the mark 24) relative to the mold 6. As a result, the insert positions of the pair of insert parts 34, 36 coincide with the pair of insert holes 14, 16, respectively, and correction of the insert execution position of the hand unit 28 relative to the mold 6 is completed.

[0084] In this embodiment, the above difference is calculated for one of the multiple marks 18 to 24 to obtain the correction value θxy, but this is not limited to this. The above difference may be calculated for each of the multiple marks 18 to 24, and the average value of these multiple differences may be obtained as the correction value θxy.

[0085] [3. Effects] In this embodiment, when the mold 6 is displaced from the appropriate position on the die plate 4 to a displaced position, there is no need to manually modify the operation program or teaching position of the articulated robot 8, so the insert execution position of the hand portion 28 of the articulated robot 8 relative to the mold 6 can be easily corrected.

[0086] (Modification) Although the position correction device according to the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

[0087] In the above embodiment, each of the marks 18 to 24 is formed in a substantially circular shape, but this is not limiting and the marks may be formed in any shape, such as an elliptical shape or a polygonal shape.

[0088] In the above embodiment, the marks 18 to 24 are arranged near each of the four corners of the surface 6a of the mold 6, but this is not limiting and the marks may be arranged at any desired positions on the surface 6a of the mold 6.

[0089] Furthermore, in the above embodiment, a plurality of marks 18 to 24 are arranged on the surface 6a of the mold 6, but this is not limiting, and only one mark may be arranged.

[0090] The present invention may be embodied as a computer program for causing a computer to execute the position correction method according to any one of the first to sixth aspects. [Industrial Applicability]

[0091] The present invention can be applied, for example, as a position correction device used in insert molding. [Explanation of symbols]

[0092] 2. Part insertion device 4 Die Plate 6. Mold 6a surface 8 Articulated Robots 10. Camera 12 Position correction device 14,16 Insert hole 18,20,22,24 marks 26 Articulated arm 28 Hand section 28a Support part 28b Grip part 30 Tool flange 32 Rotation axis 34,36 Insert parts 38 Processors 40 Memory 42 Matching Images 44,46,48,54,56,58 Images 50 straight line 52 Reference Line

Claims

1. A position correction method for correcting a position of a hand unit of an articulated robot with respect to a die, comprising the steps of: (a) when the mold is located at an appropriate position, a camera disposed on the hand unit captures an image of a mark arranged on a surface of the mold so that the mark is located at a predetermined position in the captured image; (b) calculating a mark reference coordinate indicating a reference position of the mark based on a robot coordinate indicating a position of the articulated robot when the mark was photographed in (a); (c) when the die is displaced from the appropriate position to a displacement position, photographing the mark with the camera while the articulated robot is positioned at a teaching point, which is the position of the articulated robot when the mark was photographed in (a); (d) calculating a mark displacement coordinate indicating a displacement position of the mark based on a displacement amount of the mark from the predetermined position in the captured image captured in (c); (e) calculating a correction value for the position of the hand unit relative to the die based on the mark reference coordinates and the mark displacement coordinates. Position correction method.

2. The articulated robot comprises: An arm portion; the hand unit is disposed at a tip end of the arm unit and is rotatable about a rotation axis relative to the arm unit, In the step (a), (i) when the hand unit is in a first rotational position relative to the arm unit, the camera photographs the mark so that the mark is located at the predetermined position in a first captured image, and then (ii) when the hand unit is in a second rotational position rotated a predetermined rotation angle from the first rotational position relative to the arm unit, the camera photographs the mark so that the mark is located at the predetermined position in a second captured image, In the step (b), the mark reference coordinates are calculated based on first robot coordinates indicating a position of the articulated robot when the first photographed image was captured, second robot coordinates indicating a position of the articulated robot when the second photographed image was captured, and the predetermined rotation angle. The position correction method according to claim 1 .

3. The mold is formed in a rectangular shape, the marks include a first mark, a second mark, a third mark, and a fourth mark arranged corresponding to four corners on the surface of the mold, respectively; the first mark and the fourth mark are arranged diagonally, and the second mark and the third mark are arranged diagonally, In the step (e), (i) a displacement amount of the mark in two mutually perpendicular directions from the predetermined position in the captured image captured in the step (c), and (ii) first intersection coordinates indicating a position of an intersection between a first line connecting the mark reference coordinates indicating the reference position of the first mark and the mark reference coordinates indicating the reference position of the fourth mark and a second line connecting the mark reference coordinates indicating the reference position of the second mark and the mark reference coordinates indicating the reference position of the third mark when the mold is located at the appropriate position are calculated; a second intersection coordinate indicating an intersection position between a third line connecting the mark displacement coordinate indicating the displacement position of the first mark and the mark displacement coordinate indicating the displacement position of the fourth mark and a fourth line connecting the mark displacement coordinate indicating the displacement position of the second mark and the mark displacement coordinate indicating the displacement position of the third mark in a state in which the die is displaced from the appropriate position to the displacement position; and a second intersection coordinate indicating an intersection position between the first line and the third line in a state in which the first intersection coordinate and the second intersection coordinate coincide with each other. The position correction method according to claim 1 .

4. The marks are arranged on the surface of the mold. The position correction method according to claim 1 .

5. The mark is formed in a substantially circular shape. The position correction method according to any one of claims 1 to 3.

6. The mold is a mold for insert molding having an insert hole formed in the surface, The hand portion of the articulated robot is capable of gripping an insert part to be inserted into the insert hole. The position correction method according to any one of claims 1 to 3.

7. A method for correcting a position according to claim 1, program.

8. A position correction device for correcting a position of a hand part of an articulated robot with respect to a die, comprising: A processor and a memory, The processor uses the memory to: (a) when the mold is located at an appropriate position, a camera disposed on the hand unit photographs a mark arranged on a surface of the mold so that the mark is located at a predetermined position in the photographed image; (b) calculating a mark reference coordinate indicating a reference position of the mark based on a robot coordinate indicating a position of the articulated robot when the mark was photographed in (a); (c) when the die is displaced from the appropriate position to a displacement position, the mark is photographed by the camera while the articulated robot is positioned at a teaching point, which is the position of the articulated robot when the mark was photographed in (a); (d) calculating a mark displacement coordinate indicating a displacement position of the mark based on an amount of displacement of the mark from the predetermined position in the captured image captured in (c); (e) Executing control to calculate a correction value for the position of the hand unit relative to the die based on the mark reference coordinates and the mark displacement coordinates. Position correction device.

Images